Conventional hair bands are provided on their outer surface with different patterns in decoration or color. However, the pattern is unchangeable to a specific hair band. Hair bands of different patterns are needed by female customers to match with different clothes. To do so, they have to buy several bands different in color or decoration. Each of the bands can only be used separately and therefore the cost is high. Furthermore, young girls require more variations of hair bands. Therefore, hair bands that not only can be used separately, but also can be combined together to form bands of different patterns are highly demanded.